#include <algorithm>
#include <fstream>
#include <vector>
#include <stack>

#define fi first
#define se second

using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
int const N = 2e5 + 3;
typedef pair<int,int> pii;
int n , m , biconexe;
int idx[N] , low[N];
stack<pii> st;
vector<int> v[N];
vector<int> bcx[N];
void dfs(int x , int t = -1){
    idx[x] = ++idx[0];
    low[x] = idx[x];
    int fii(0);
    for(int y : v[x]){
        if(y == t)
            continue;
        if(idx[y]){
            low[x] = min(low[x] , idx[y]);
            if(idx[x] >= idx[y])
                st.emplace(x , y);
            continue;
        }
        ++fii;
        st.emplace(x , y);
        dfs(y , x);
        if((t == -1 && fii > 1) || (t != -1 && low[y] >= idx[x])){
            ++biconexe;
            int a , b;
            do{
                a = st.top().fi;
                b = st.top().se;
                st.pop();
                bcx[biconexe].push_back(a);
                bcx[biconexe].push_back(b);
            }while(a != x || b != y);
        }
    }
}
int main()
{
    fin >> n >> m;
    for(int i = 1 ; i <= m ; ++ i){
        int a , b;
        fin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for(int i = 1 ; i <= n ; ++ i){
        if(idx[i])
            continue;
        dfs(i);
        if(st.empty())
            continue;/*
        ++biconexe;
        while(!st.empty()){
            bcx[biconexe].push_back(st.top().fi);
            bcx[biconexe].push_back(st.top().se);
            st.pop();
        }*/
    }
    fout << biconexe << '\n';
    for(int i = 1 ; i <= biconexe ; ++ i){
        sort(bcx[i].begin() , bcx[i].end());
        bcx[i].erase(unique(bcx[i].begin() , bcx[i].end()) , bcx[i].end());
        for(int j : bcx[i])
            fout << j << ' ';
        fout << '\n';
    }
    return 0;
}